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Original-commit: flang-compiler/f18@92f0c397f6
Reviewed-on: https://github.com/flang-compiler/f18/pull/225
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peter klausler 2018-11-02 14:48:28 -07:00
parent 9ddf39811c
commit 2b2ea8d1a5
1 changed files with 10 additions and 13 deletions
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flang/documentation/C++style.md
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@ -190,6 +190,7 @@ the definition of an external destructor.
optional deep copy semantics; reassignable.
Often better than a reference (due to ownership) or `std::unique_ptr<>`
(due to non-nullability and copyability).
Can be wrapped in `std::optional<>` when nullability is required.
* `CountedReference<>`: A nullable pointer with shared ownership via
reference counting, null by default, shallowly copyable, reassignable.
Safe to use *only* when the data are private to just one
@ -199,19 +200,15 @@ of that standard feature is prohibitive.
A feature matrix:
| pointer | nullable | default null | owning | reassignable | copyable |
| ------- | -------- | ------------ | ------ | ------------ | -------- |
| `*p` | yes | no | no | yes | shallowly |
| `&r` | no | n/a | no | no | shallowly |
| `unique_ptr<>` | yes | yes | yes | yes | no |
| `shared_ptr<>` | yes | yes | yes | yes | shallowly |
| `OwningPointer<>` | yes | yes | yes | yes | no |
| `Indirection<>` | no | n/a | yes | yes | optionally deeply |
| `CountedReference<>` | yes | yes | yes | yes | shallowly |
Note that `std::optional<Indirection<>>` checks all the boxes, if you
need a nullable `Indirection<>`.
| pointer | nullable | default null | owning | reassignable | copyable | undefined type ok? |
| ------- | -------- | ------------ | ------ | ------------ | -------- | ------------------ |
| `*p` | yes | no | no | yes | shallowly | yes |
| `&r` | no | n/a | no | no | shallowly | no |
| `unique_ptr<>` | yes | yes | yes | yes | no | no |
| `shared_ptr<>` | yes | yes | yes | yes | shallowly | no |
| `OwningPointer<>` | yes | yes | yes | yes | no | yes |
| `Indirection<>` | no | n/a | yes | yes | optionally deeply | no |
| `CountedReference<>` | yes | yes | yes | yes | shallowly | no |
### Overall design preferences
Don't use dynamic solutions to solve problems that can be solved at